Photon counting detectors with energy binning can improve CT performance by counting and binning each x-ray detected. Photon counting x-ray detectors applied to mammography and radiography have shown a dose reduction of 40% to 400% while maintaining sufficient contrast for these applications. For use in CT these detectors are limited, due to an upper bound in terms of their maximum count rate, and advances in maximum count rate capabilities is needed. In order to overcome count rate limitations, new technological developments in reducing the size of application specific integrated circuits (ASICs) has been applied to reading out semiconductor detectors. These advancements, along with improvements to the cost and reliability of the compound semiconductor cadmium telluride (CdTe), allow us to develop a photon counting detector and read-out technology for CT. Therefore the overall goal of this Fast Track Phase I/Phase II proposal is to develop a photon counting CT detector with energy binning and read-out that is capable of producing energy resolved CT scan which can deliver less radiation dose and differentiate between tissue types.